Massive machinery at work in the open-pit Wyodak coal mine in the coal-rich Powder River Basin outside Gillette, Wyoming.… https://www.rawpixel.com/image/434368/free-photo-image-mine-coal-tractorFree Image from public domain licenseMassive machinery at work in the open-pit Wyodak coal mine in the coal-rich Powder River Basin outside Gillette, Wyoming.… https://www.rawpixel.com/image/434361/free-photo-image-mining-public-domain-trains-carol-highsmithFree Image from public domain license